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Geographic
range: Nearctic: Found within a large area due to their migratory
behavior. According to the studies, animals can annually cover up
to 21,000 km during their migrations. From the coastal waters of the
Pacific Ocean in the Gulf of Alaska south to Baja California. Foraging
migrations by males and females are made separately, twice annually.
Males migrate north to the Aleutian Islands and the Gulf of Alaska,
while females, who don't travel as far north, migrate further west
to more open ocean.
Physical characteristics:
The body is generally brown although variations to this coloration
can be seen. Males are usually a darker brown, while females are a
light tan color. Hair cover is largely reduced on adults and becomes
completely absent for a short time after molting. Newborns have black
hair, which they lose after weaning. Northern elephant seals have
two, lobed hind flippers. The most prominent s feature to the male
body is the inflated proboscis on male's face, which starts developing
around the second year of age and reaches its full size at 8 years,
when males are sexually mature. young males begin development of the
proboscis at 2 years of age, but it is not fully developed until the
animal reaches its 8th year of maturity. Northern elephant seals are
large animals, females typically weigh 600 to 900 kg and males up
to 2300 kg. Females reach a length of around 3 m, while males grow
to up to 4.0 m to 5.0 m. Also teeth are dimorphic, males posses large
canines which are used for territorial fights.
Food
habits: Males and females of Northern elephant seal display
different foraging techniques focused on different food items. Males
remain closer to the shore during their annual feeding migrations
and usually forage diving to the ocean floor. They also catch larger
pray, as sharks and skates. Females forage more on the open ocean
and exhibit more pelagic diving. Their main food items include more
invertebrates, like squid. While on land, both males and females don't
receive any food at all. During this period, all necessary energy
is broken down from fat stored in form of blubber.
Reproduction
& Behavior: Northern elephant seals and territorial and
polygynous Dominant males defend during the mating season a territory
with a group of females. Less dominant males usually stay at the perimeter
of the colony and occasionally attempt to mate with females guarded
by dominant males. This behavior usually results in aggressive fights
in between the defendant of the colony and the aggressor and can be
dangerous not only to the animals involved, but also to young pups,
who many times result killed by trampling.
Breeding season extends from December to March. Females are receptive
only for a short period of about 4 days. Implantation of the fertilized
egg doesn't follow copulation immediately. About 3 months delay follows
after which the egg attaches outwardly to the uterine wall and continues
its development. Including the time of delayed implantation, the gestation
lasts for 1 year. This allows both giving birth and mating to occur
in the same time frame, during the short period of the year when these
animals are aggregated in terrestrial colonies.
Females become sexually mature at 2 years of age, but usually have
their first pup in the 4th year of life. Males are sexually mature
at the age of 6 or 7, but only occasionally are allowed to mate before
they reach the age of 9 or 10, when they become successful competitors
to the dominant males.
Pups are fed very nutritious milk for a short period of about 30 days.
Weight gain during this time is dramatic. After weaning the mother
returns to the sea and pups are left alone without parental care on
land for another 10 -12 weeks forming groups, where they learn to
swim and forage farther on the sea.
Habitat:
Sandy, rocky or muddy shores of the coastline, particularly
on offshore islands.
Conservation:
Populations of the Northern elephant seal are not in direct danger
today although once thought to be extinct. Nevertheless the bottle
neck effect, which occurred in the history could nowadays be a concern
for the possibility of the population to be vulnerable to disease
or reproductive failure.
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